The promise of static typing

* Project management strategy for the repo/project.

* Commercial vs. non-commercial project.

* Ability and experience of the developers.

* Popularity of the project.

* Type of project (library, application, etc.)

I suspect all of these will correlate in a meaningful way with the language choice. Commercially produced or consumed projects may be more likely to have comprehensive bug reporting/tracking, and are more likely to be in a "mainstream" language, for instance.

Like Torvalds says, with enough eyeballs, all bugs are shallow. A corollary to that could be that without knowing how many eyeballs there are, and how well they can see, you don't really know how many bugs there are, either.

Considering this I'm not surprised at all to see that Java, Python and C++ repositories have a higher "bug density" than Clojure, Go or Erlang ones.

Edit: Figured it out (total bugs / repo). Seems like controlling for overall project size is an important missing component of this analysis.

The proportion of Haskell libraries for tasks like string padding is probably lower than the proportion of ruby or js libraries, for example.